Eastern Dwarf Tree Frog
Litoria fallax

A tiny frog, with the males (such as this one) being only just over 2 cm in length and the females a little larger at 2.5 - 3 cm. They occur down the eastern side of Australia from a little north of Cairns to a little further north of Sydney and overlap at the top of their range with the very similar Northern Dwarf Tree Frog, which has a paler strip running down the side and a rounder snout. The second photo gives an idea of just how small they are...
 

1-2: Abbatoir Swamp, Julatten, Qld, 12/03/2012